<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>

</body>
<script>
    var  arrs = ['a','b','c','d'];
    for (key in arrs){
        console.log(arrs[key])
    }

    for (value of arrs){
        console.log(value)
    }

    for (let  i=0;i<arrs.length;i++){
        console.log(arrs[i]);

    }
</script>
</html>